1. Field of the Invention
The invention relates to a drive train transmission apparatus, preferably for a front axle of a floor transport vehicle with at least one transmission stage, comprising a housing, a drive sprocket, wherein the drive sprocket is coupled with a drive motor which is fixed to the transmission housing, a hollow gear, wherein the rotational axis of the drive sprocket and the hollow gear are disposed offset from each other, and a running wheel fixed in a torque-proof fashion with the hollow gear.
2. Introduction
Transmissions of the kind disclosed herein are typically required for drive wheels for floor transport vehicles. Such transmissions must preferably be built as small as possible, and additionally have to be suitable for carrying large loads. In order to assure the stability of the vehicle, the transmission apparatus must efficiently transfer drive torque to the running wheels and should not adversely influence the dimensions of the vehicle with respect to width and height. It is also of particular importance that the vehicle's center of gravity be located as low as possible, in order to reduce the risk of tipping. Furthermore, it has to be considered with transmissions of this kind that the loads the vehicle receives, which may be as large as five tons, can be transferred through the transmission housing to the running wheel.
U.S. Pat. No. 5,558,174 discloses a transmission assembly for floor transport vehicles, such as forklifts, which is provided for driving one of two front load-bearing drive wheels. For power generation, an electric motor is used, which drives a bevel gear mounted in a torque-proof fashion on a drive shaft. The bevel gear teeth mesh with a gear on a drive axle, mounted such that its axis is parallel with the rotational axis of the drive wheel and normal to the rotational axis of the electric motor and its drive shaft. The drive axle comprises a gear on its distal end which meshes with the interior ring gear of the hub of the drive wheel. The assembly disclosed in the '174 patent inefficiently transfers drive torque, in part because the rotational axis of the electric motor and its drive shaft is normal to the rotational axis of the drive wheel. Additionally, the physical size of the transmission makes the component cumbersome and, as substantial components are mounted relatively high from the floor, unnecessarily raises the center of gravity of the vehicle. Finally, the transfer of the loads to the running wheels is not performed in an optimum manner, in part because the assembly requires a drive shaft at least the length of the radius of the electric motor's armature stack.
3. Objects of the Invention
It is an object of the present invention to provide a transmission apparatus, which is compact, can be mounted in a fashion that keeps the vehicle's center of gravity low, uses relatively few components, and simultaneously allows a high load transfer through the housing onto the running wheels.